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Epitaxial grown Gallium nitride (GaN) thin film on sapphire was irradiated with Cu ions at various fluences (5×10¹⁴, 1 ×10¹⁵ and 5×10¹⁵cm^-2). The level of lattice disorder, as measured by Rutherford backscattering spectrometry and channeling (RBS/C), gradually increases with the increasing of ions fluence. Lattice amorphization is observed for the sample irradiated with fluence of 5×10¹⁵cm^-2 which is also confirmed by X-ray diffractometer (XRD) analysis. It was found that both Raman modes of GaN layer clearly shifted with Cu⁺ fluences. Both Raman and X-ray analyses explore that Cu atom substituted into Ga sites. Atomic force microscopy (AFM) images show the irradiated GaN surface roughness increases with the increasing ions fluence. The UV-visible transmittance spectrum and ellipsometric measurements show a decrease in the band gap value after irradiation of Cu ions in the GaN film. Moreover, the optical constants (n and k) of the films vary with the increasing of Cu ion fluences.

The present work determined the band gap energy of PbI₂ equal to 2.31 eV by amplitude measurement of the photoacoustic (PA) signal using the front side detection configuration. Furthermore, the thermal properties were obtained from the phase recording of the PA signal at the characteristic frequency 55 Hz of the single crystal (250 μm). These properties have also been compared with the earlier reported values under identical experimental conditions by amplitude recording of the PA signal on the same PA spectrometer.

The band gap bowing parameter of the new semiconductor Tl_xAl_1-xAs alloys are investigated numerically based on first-principles calculations and the local density approximation. A 16-atom supercell is used to model for the ternary Tl_xAl_1-xAs alloys. The alloy's lattice constants obey Vegard's law well. Band gap bowing coefficients show very strong composition dependence. The results suggest that the unstrained band gap bowing parameter of the ternary Tl_xAl_1-xAs alloys is b = 1.9754 eV. The results also suggest that the composition-dependent band gap energy of the zincblende alloys can be expressed by a third-order polynomial equation, E_g(x) = -7.2064x³ + 14.8397x²-10.016x + 2.2217 eV.

Indium sulfide (In₂S₃) thin films were deposited onto the glass substrates by a low cost simple spray pyrolysis technique at 300°C temperature. Aqueous solution of indium chloride and thiourea were used to deposit the binary In-S film. The deposited thin films were annealed at 400° and 500°C temperatures and characterized structurally, optically and electrically using EDX, X-ray diffraction, UV-visible spectroscopy and four probe van der Pauw methods. The optical constants such as refractive index and extinction coefficient are calculated from absorbance and transmittance data from 300 to 1100 nm wavelength. The optical transmittance increased after annealing at 400° and 500°C. The band gap energy was reduced from 2.90 to 2.50 eV after annealing the as deposited films. The electrical conductivity as well as the activation energy was increased after annealing the samples.

Nowadays, the superior properties of carbon-based materials especially nano structural derivation like graphene and graphene oxide (GO) spot light to the researchers. The GO has been suggested as an alternate material in device miniaturization due to its atomic structure. The memristors and nonvolatile memories are settled in these categories as a solution for the scaling limitation problem in the Moor’s law. Therefore, the GO can influence the memristor performance and characteristics. The current–voltage characteristics as the most significant parameter in the memristor design are considered. On the other hand $I$–$V$ characteristic depends on the active layer (GO) bandgap energy in the metal/oxide/metal structure and therefore, needs to be explored. In the GO-based memristor, the bandgap energy can be changed by the percentage of the oxygen groups in comparison to the carbon on graphene sheets. Thus, the other parameters are overstated by the bandgap energy. In the presented work, the energy bandgap of a high epoxy group content of GO sheets is engineered. The opening of the bandgap in the graphene oxide by high epoxy groups content with the ratio of (O/C $=$ 50%) is studied. In other words, the oxygen adsorption effect on the Hamiltonian of the system is explored. For the proposed structure, the bandgap energy is modeled and the acceptable value (approximately equal to 2.799ev for epoxy groups) is obtained. Moreover, the hydroxyl group adsorption effect on the bandgap of the graphene oxide by high content hydroxyl group is considered (approximately equal to 2.647ev for epoxy groups). Consequently, the different absorption energy effects on the bandgap of the GO is participated and the opening bandgap in the range of 2ev to 3ev is obtained. The excitonic effect on the suggested model by epoxy groups and hydroxyl groups is explored and it is realized that the energy levels in the Dirac points of epoxy groups are closer than those of the hydroxyl groups.

With the increasing demand of high-power and pulsed power electronic devices, environmental-friendly potassium sodium niobate ((Na${}_{0.5}$K${}_{0.5}$)NbO₃, KNN) ceramic-based capacitors have attracted much attention in recent years owning to the boosted energy storage density ($W_{\mathrm{\text{rec}}}$). Nevertheless, the dielectric loss also increases as the external electric field increases, which will generate much dissipated energy and raise the temperature of ceramic capacitors. Thus, an effective strategy is proposed to enhance the energy storage efficiency ($\eta$) via tailoring relaxor behavior and bad gap energy in the ferroelectric 0.9(Na${}_{0.5}$K${}_{0.5}$)-NbO₃–0.1Bi(Zn${}_{2/3}$(Nb${}_x$Ta${}_{1-x}$)${}_{1/3}$)O₃ ceramics. On the one hand, the more diverse ions in the B-sites owing to introducing the Ta could further disturb the long-range ferroelectric polar order to form the short–range polar nanoregions (PNRs), resulting in the high $\eta$. On the other hand, the introduction of Ta ions could boost the intrinsic band energy gap and thus improve the $E_{\mathrm{\text{b}}}$. As a result, high $W_{\mathrm{\text{rec}}}$ of 3.29 J/cm³ and ultrahigh $\eta$ of 90.1% at the high external electric field of 310 kV/cm are achieved in $x$ = 0.5 sample. These results reveal that the KNN-based ceramics are promising lead-free candidate for high-power electronic devices.